1. Field of the Invention
The present invention relates generally to twin clutch type speed-change apparatuses. More particularly to a twin clutch type speed-change apparatus that can detect an engagement state of a dog clutch by use of the rotational speed difference between an inner main shaft and an outer main shaft and of a signal outputted from a gear position sensor.
2. Description of Background Art
A transmission is known that includes a plurality of gear pairs between a main shaft and a counter shaft that are configured to execute a shifting operation by turning a shift drum arranged parallel to the shafts to axially slide a shift fork engaged with the shift drum. Such a transmission can detect a currently selected speed step number by detecting the turning angle of the shift drum.
Japanese Utility Model Laid-Open No. Sho 61-202744 discloses a configuration for detecting a speed step number corresponding to the turning position of a shift drum on the basis of a signal outputted by a gear position sensor mounted at the end of the shift drum.
In addition, a multi-stage transmission is known in sequential transmissions using a shift drum. This multi-stage transmission enables an automatic or semi-automatic transmission control by driving a shift drum or a clutch by means of an actuator or the like. Such transmissions generally transmit a rotational drive force between coaxially adjacent speed-change gears by means of a dog clutch consisting of dog teeth and dog apertures. The dog clutch provides high-efficiency for transmitting a rotational drive force. On the other hand, a rotational speed difference may be large between a speed-change gear formed with dog teeth and a speed-change gear formed with dog apertures. In such a case, the dog clutch sometimes causes a dog-tip caught state where a dog tooth is not drawn out of a corresponding dog aperture or a dog-tip abutting state where a dog tooth is not inserted into a corresponding dog aperture. To surely execute a shifting operation by electrically driving a clutch or the shift drum, it is preferred that the engagement state of the dog clutch described above can be detected. However, to detect the engagement state of the dog clutch by the gear position sensor as disclosed in Japanese Utility Model Laid-Open No. Sho 61-202744, it is necessary to significantly increase the sensor accuracy to more finely detect the turning angle of the shift drum.